<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="add" method="post">
    姓名<input type="text" name="username"><br>
    生日<input type="text" name="birthday"><br>
    性别<input type="radio" name="sex" value="man" checked>男
    <input type="radio" name="sex" value="woman">女<br>
    <input type="submit" value="点击添加">
</form>
</body>
</html>